This invention relates to protective circuits for electrical power lines whereby damage to electrical loads from transient and surge voltages is prevented.
Many protective circuits have been devised for electrical power lines designed to detect and suppress transient voltages and/or surges of the power source that may cause damage to electrical equipment to which the power lines are connected. Certain types of such protective circuits utilize a Zener diode device that is rendered conductive when a predetermined breakdown voltage applied thereacross is exceeded. Such Zener devices are thereby operative to clip excessively high peak voltages that may occur. Problems arise, however, in providing Zener diodes capable of handling transient loads over an extended period of time because of heat developed. Various capacitive filters and nonlinear resistors have been utilized for such protective circuits in order to deal with other problems such as rapid response time and preventing unintended breakdown of the Zener diode.
It is therefore an important objective of the present invention to provide a protective circuit assembly which is operative to monitor power lines and suppress short term transient currents by use of Zener diodes in a more efficient and reliable manner.